Search results for "Postsynaptic potential"
showing 10 items of 371 documents
The inhibitory neural circuitry as target of antiepileptic drugs.
2001
Impairments and defects in the inhibitory neurotransmission in the CNS can contribute to various seizure disorders, i.e., gamma-aminobutyric acid (GABA) and glycine as the main inhibitory neurotransmitters in the brain play a crucial role in some forms of epilepsy. Recent advances in deciphering the molecular basis of the GABAergic and glycinergic systems has been achieved by means of cloning techniques and gene targeting strategies in animals, contributing to the understanding of drug action. As well, several anticonvulsive substances emerged which target key molecules of the inhibitory systems. Employment of recombinant expression systems, including, but not restricted to the inhibitory c…
Functional evidence for GABA as modulator of the contractility of the longitudinal muscle in mouse duodenum: Role of GABAA and GABAC receptors
2007
We investigated, in vitro, the effects of gamma-aminobutyric acid (GABA) on the spontaneous mechanical activity of the longitudinal smooth muscle in mouse duodenum. GABA induced an excitatory effect, consisting in an increase in the basal tone, which was antagonized by the GABA(A)-receptor antagonist, bicuculline, potentiated by (1,2,5,6-Tetrahydropyridin-4-yl)methylphosphinic acid hydrate (TPMPA), a GABA(C)-receptor antagonist and it was not affected by phaclofen, a GABA(B)-receptor antagonist. Muscimol, GABA(A) receptor agonist, induced a contractile effect markedly reduced by bicuculline, tetrodotoxin (TTX), hexamethonium and atropine. Cis-4-aminocrotonic acid (CACA), a specific GABA(C) …
Refuting the challenges of the developmental shift of polarity of GABA actions: GABA more exciting than ever!
2012
International audience; During brain development, there is a progressive reduction of intracellular chloride associated with a shift in GABA polarity: GABA depolarizes and occasionally excites immature neurons, subsequently hyperpolarizing them at later stages of development. This sequence, which has been observed in a wide range of animal species, brain structures and preparations, is thought to play an important role in activity-dependent formation and modulation of functional circuits. This sequence has also been considerably reinforced recently with new data pointing to an evolutionary preserved rule. In a recent ``Hypothesis and Theory Article,'' the excitatory action of GABA in early …
Ontogeny of the human amygdala.
2003
Data on the fetal development of the human amygdala is reviewed with special reference to major ontogenetic events. In the fifth gestational month, the inferior portion of the amygdala reveals cell-dense columns merging with the ganglionic eminence (proliferative zone) in Nissl-stained sections. These columns contain vimentin-positive fibers and can therefore be regarded as migrational routes. In the sixth and seventh months, distinct reorganization of the cytoarchitectonics takes place. The sequential occurrence of afferens can be visualized using anti-GAP-43; moreover, outgrowing axons appear to reach the periphery of the ganglionic eminence. The latter may thus represent an intermediate …
The diversity of GABAA receptors. Pharmacological and electrophysiological properties of GABAA channel subtypes.
1998
The amino acid gamma-aminobutyric-acid (GABA) prevails in the CNS as an inhibitory neurotransmitter that mediates most of its effects through fast GABA-gated Cl(-)-channels (GABAAR). Molecular biology uncovered the complex subunit architecture of this receptor channel, in which a pentameric assembly derived from five of at least 17 mammalian subunits, grouped in the six classes alpha, beta, gamma, delta, sigma and epsilon, permits a vast number of putative receptor isoforms. The subunit composition of a particular receptor determines the specific effects of allosterical modulators of the GABAARs like benzodiazepines (BZs), barbiturates, steroids, some convulsants, polyvalent cations, and et…
3H-1,2-benzoxathiepine 2,2-dioxides: a new class of isoform-selective carbonic anhydrase inhibitors
2017
Abstract A new chemotype with carbonic anhydrase (CA, EC 4.2.1.1) inhibitory action has been discovered, the homo-sulfocoumarins (3H-1,2-benzoxathiepine 2,2-dioxides) which have been designed considering the (sulfo)coumarins as lead molecules. An original synthetic strategy of a panel of such derivatives led to compounds with a unique inhibitory profile and very high selectivity for the inhibition of the tumour associated (CA IX/XII) over the cytosolic (CA I/II) isoforms. Although the CA inhibition mechanism with these new compounds is unknown for the moment, we hypothesize that it may be similar to that of the sulfocoumarins, i.e. hydrolysis to the corresponding sulfonic acids which therea…
Effects of histamine on dentate granule cells in vitro
1990
Abstract Hippocampal slices from rat brain were exposed to histamine and related substances in a perfusion chamber. Granule cells of the dentate gyrus were studied with conventional extra- and intracellular recording and a single electrode voltage clamp. Histamine caused, through activation of H 2 -receptors, a small depolarization, an increase in the number of synaptic and action potentials, a block of the long lasting (but not the early) component of spike afterhyperpolarizations and a reduction of the accommodation of action potential firing. These effects were mimicked by forskolin (suggests activation of adenylate cyclase). In voltage clamp, histamine blocked a long lasting calcium-dep…
Effect of claustrum stimulation on neurons of the contralateral medial oculomotor area, in the cat
1990
In chloralose-anaesthetized cats, the extracellular spontaneous unitary activity was recorded from 157 neurons, located in the medial oculomotor area. 98 units were identified as projecting onto the superior colliculus. Electrical stimulations of the contralateral claustrum provoked, on 13 of these cells, an excitatory effect, lasting 10-35 ms and appearing with a latency of 20-50 ms. Full length section of the corpus callosum totally abolished the contralateral claustrum effect. The results suggest that in the cat, the claustrum may have a role in the bilateral control of the visuo-motor performance.
Reduction in the Motoneuron Inhibitory/Excitatory Synaptic Ratio in an Early-Symptomatic Mouse Model of Amyotrophic Lateral Sclerosis
2010
Excitotoxicity is a widely studied mechanism underlying motoneuron degeneration in amyotrophic lateral sclerosis (ALS). Synaptic alterations that produce an imbalance in the ratio of inhibitory/excitatory synapses are expected to promote or protect against motoneuron excitotoxicity. In ALS patients, motoneurons suffer a reduction in their synaptic coverage, as in the transition from the presymptomatic (2-month-old) to early-symptomatic (3-month-old) stage of the hSOD1(G93A) mouse model of familial ALS. Net synapse loss resulted from inhibitory bouton loss and excitatory synapse gain. Furthermore, in 3-month-old transgenic mice, remaining inhibitory but not excitatory boutons attached to mot…
P3‐039: Axonal neuritic pathology induces early presynaptic alterations in ps1/APP Alzheimer's mice hippocampus
2011
Loss of neurons in the hippocampus correlates with memory impairment in AD. Significant early reduction in the numerical density of hippocampal SOM interneurons was found in single (APPswe) and double (APPswe/ PS1dE9 and APPswe/TauP301S-G272V) transgenic models based on APP over expression and amyloid production. However, this inhibitory population was unaffected in age-matched single PS1 and tau transgenic mice as well as nontransgenic controls. Whereas SOM neuron loss in APPswe/PS1dE9 was associated to the onset of extracellular amyloid pathology in double APP/ tau mice this loss preceded plaque formation. Conclusions: As in human AD, somatostatin cell loss is a common early pathological …